An environmental problem has come to the fore and a solar cell is noted as a clean energy source. The demand of a solar cell is sharply increasing on residential purposes also in our country. A silicon-based solar cell is excellent in reliability and cell efficiency, and the silicon-based solar cell makes up about 80% of photovoltaic system. In order to increase the demand and decrease power generation cost, it is required to obtain a silicon material with low cost. At present as for a method for producing high purity silicon, most makers use Siemens method in which trichlorosilane is thermally decomposed. However, this method has a limit in electric power consumption rate, and it is hard to further decrease the cost.
As a method instead of a thermal decomposition, a method of reducing chlorosilane using zinc or aluminum to obtain silicon is proposed. For example, a method for producing silicon, in which fine aluminum particles are reacted with silicon tetrachloride gas, is known.
JP-A-2-64006 (U.S. Pat. No. 4,919,913) discloses a method for producing silicon, in which a gaseous silicon compound represented by a formula of SiHnX4-n (wherein X is halogen and n is from 0 to 3) is reacted with aluminum. In this method, the gaseous silicon compound is contacted with a molten metal surface in which pure aluminum or Al—Si alloy is finely dispersed.
JP-A-60-103016 discloses a method for producing pure silicon, which includes the steps of suppylying silicon tetrachloride gas to a silicon alloy or a silicon copper alloy with a high silicon content at a high temperature to generate a gas, cooling the gas appropriately and deposit a partial amount of silicon so as to make impurities to be absorbed in the deposited part of silicon, and then cooling the gas.
Further, JP-B-36-8416 discloses a method of reducing silicon tetrachloride with aluminum which is evaporated at a high temperature.